"I guess that's why they do it — to make people realize they should. It worked on me," Leff said.

More than 70 schools in Sonoma County were expected to participate in the annual event that is staged to give both students and parents a sense of what life could be like if they shelve the car keys.

The event can help allay parents' fears of riding bikes or walking to school, while also giving officials a better sense of what it takes to keep people safe on sidewalks and streets, said Tina Panza, director of Safe Routes to Schools, an organization that spearheaded the event.

"I personally think that there are more risks to not encouraging healthy, active lifestyle than there are for kids biking and walking to school," she said.

At Casa Grande, a contingent of cyclists rolled onto campus with former professional cyclist Steven Cozza who agreed to lead a bike train that picked up riders at predetermined locations Wednesday morning.

"I think the change is going to come in baby steps," Cozza said of the default mode of driving everywhere, including to school. "People should make it a goal to ride one day a week, then maybe two days a week."